Have too many. Just in the room I'm sitting in right now I have 5 working towers, 2 laptops, a netbook, a tablet, a Raspberry Pi and an Android mini-pc. My 2 daughters each have a tower, netbook and tablet. My son has a tower, laptop, netbook and tablet. My wife has a netbook. All of these connect to my network. I don't have any plans to add or delete any of these computers right now but that could change at any time.
How long to accumulate all of these? I got my first computer in 1984 but the oldest of my current computers is probably no older than 1999 or so. I built my first in 1985 and can't guess at how many computers I've built or purchased since but quite a few.
Up until a few months ago, I had a vintage computer collection of about 25 computers from the DOS days. However, I sold/gave away all of those because I lost interest in that hobby.